Patent Document 1 discloses a cooling device including an ebullient cooling system in which a refrigerant cools the internal combustion engine by boiling in an internal combustion engine, and a rankine cycle system in which the refrigerant discharged from the internal combustion engine is supplied, as a conventional cooling device for the internal combustion engine. Moreover, the rankine cycle system according to Patent Document 1 includes a superheater that superheats the refrigerant discharged from the internal combustion engine, a turbine to which a refrigerant (superheated steam) discharged from the superheater is supplied, and a condenser (referred to as “condenser” in Patent Document 1) that condenses a refrigerant discharged from the turbine.